I know this may not be accurate, but I went ahead and made this. I think it looks ok. http://i381.photobucket.com/albums/oo256/Chaseme0120/IronMapPack.jpg
it looks good, but the skull think is really low quality, maybe shrink it down and make it a sig. Not that everything has to be sigs, but if it's your map pack, it will advertise better if it's no a background that's only on your computer.
I'm pretty sure he meant the map pack coming with ODST, but correct me if I'm wrong. Anyway it looks pretty good. As he said the skull is low quality especially the shield. The text looks good though.